1. Field of the Invention
The present invention relates generally to flow control valves, and more particularly to a purely mechanical leak arresting flow control valve that regulates fluid flow between a minimum flow rate and a maximum flow rate, and can detect leaks below and above the minimum and maximum flow rates, respectively, and close the valve in the presence of a leak.
2. Description of Related Art
Valves used in the regulation of fluid flow are well known in the art. Valves can be used to maintain fluid flow in a particular direction, or as a safety feature to prevent too high of a flow rate or too low of a flow rate. Valves can be mechanically or electrically actuated devices that use the dynamic pressure in a fluid flow to compress a spring or move a ball, thereby allowing the fluid either to pass through the valve or be blocked by the valve.
The present invention is directed to a flow regulating valve that allows a continuous fluid flow in a predetermined range, as opposed to a pulse flow. Valves used for this purpose are useful for many applications that require a supply of a liquid or a gas, collectively a fluid, such as a washing machine, ice maker, or gas stove. The present invention includes a new feature not found in the prior art valves, namely, a purely mechanical leak detecting function. The invention is a mechanical valve that regulates the flow of fluid within a predetermined minimum and maximum flow rate, and further mechanically closes the valve when either a small or large downstream leak occurs. Thus, while prior art purely mechanical safety valves will close shut, and thereby stop the fluid flow if a major leak occurs due to the sudden increase in the fluid flow rate, the prior art valves lack the ability to close shut in the event of a small leak such as might occur due to a small breach in the downstream fluid line or the gradual failure of a downstream component. This situation could be of critical importance if, say, the fluid is hazardous or flammable, if the fluid line is not regularly maintained due to its location or conditions of use, or if subsequent damage from such a line breach would be economically or environmentally unacceptable. The response of the valve may be the only indication that a small leak has occurred. The present invention solves the problem that the prior art valves fail to address.
The present invention comprises a valve housing forming a flow chamber thereinthrough with an inlet and an outlet. Within the flow chamber is a flow arresting member comprising a pair of poppets cooperating to restrict flow at the inlet and the outlet of the flow chamber upon detection of a small or large leak downstream of the valve. The first poppet is a hollow outer poppet biased against the valve inlet by a first spring, shutting the valve to flow rates below a predetermined minimum flow rate governed by the spring constant. A second inner poppet located at least partially within the first poppet and extending through an opening in the outer poppet extends to block the outlet of the valve when a small downstream leak is detected. The second poppet is biased in the first poppet by a second spring such that the second poppet extends from the first poppet when the fluid pressure in the cavity of the first poppet exceeds the pressure at the outlet of the valve by more than a critical value determined by the second spring constant. When the second poppet fully extends from the first poppet, the second poppet plugs the outlet and closes the valve to subsequent fluid flow through the valve. This condition occurs when either a small leak or a large leak occurs downstream of the valve. Further, if a flow rate is too large, the first outer poppet will completely collapse its biasing spring such that the outlet to the valve is blocked. Thus, only a predetermined flow rate between a minimum flow rate and a maximum flow rate is permitted through the valve.